Figure 3. H&E-stained sections of retinas. Tissue fixed by freeze substitution with acetone (C) yielded what appears to be the worst overall quality of preservation, though formalin immersion (G) also reveals much evidence of shrinkage and “vacuolation.” Tissues processed through the different freeze substitution routines show little evidence of shrinkage artifacts, and exhibit good fine details, such as the outer limiting membrane, and good outer segment preservation.